1. Field of the Invention
The invention relates to abrasive wheels particularly abrasive wheels containing alumina abrasive grit with improved corner holding properties. The invention further includes a bond composition which allows for improved mechanical strength and improved corner holding properties.
2. Technology Review
Precision moving parts are being designed to run at higher outputs, higher efficiencies and longer service. These parts are for example engines (internal combustion, jet & electric), drive trains (transmissions & differentials), and bearing surfaces. In order to meet these demands, the parts must be produced with improved quality including better/stronger designs with tighter dimensional tolerances. To achieve these tolerances, the parts are being produced with better quality materials to near net or final shape and size.
Grinding wheels are often utilized for fabrication of the entire part or to impart the final dimensions. Vitreous or glass bonded grinding wheels are the wheels utilized most on metal parts. In order to produce these types of precision parts with a grinding wheel, the reverse image of the part is "dressed" into the wheel face with a diamond tool. Because the part being manufactured takes the profile of the grinding wheel, it is important that the grinding wheel retain that shape as long as possible. The ideal situation would then be to produce the precision parts with exact dimensional tolerances and with no material damage.
Typically, the grinding wheels fall out of shape or fail at a corner or a curve in the wheel. Standard fused alumina abrasive products may last through the grinding of two or three pieces before a significant change occurs in the corner of the wheel. Hence, the operators of the grinding machines may set up dressing of the wheel after every piece to avoid defects. With wheels produced using higher performing sol-gel alumina abrasive grits, the shape change in the corner of the wheel may not appear until after grinding four or five pieces and the operators of the grinding machines may plan on dressing these wheels after grinding three pieces. While the dressing frequency reduction characteristic of sol-gel alumina wheels is an improvement over standard abrasive wheels, a reduction in the loss of the alumina wheel through dressing and further gains in dressing frequency reduction are desirable goals for conventional alumina abrasive wheels.
What is needed is a better corner or form holding alumina wheel so that the dressing interval can be extended. It is therefore an object of this invention to produce an alumina abrasive grit wheel with improved corner or form holding. It is further an object of this invention to produce a bond which can be used with an alumina abrasive grit wheel to improve corner or form holding.